System for directional angle aiming of a weapon

ABSTRACT

A traverse laying system for a weapon ( 1 ) integral with a frame ( 2 ) articulated in traverse with respect to a support ( 3 ) providing a large traverse range around a first axis of rotation (G 1 ).  
     The system comprises positioning means ( 6   a,    6   b,    14 ) for the weapon ( 1 ) integral with the frame ( 2 ) in order to ensure a small lateral range of the weapon around a second axis of rotation (G 2 ) passing through the centre of gravity and perpendicular respectively to the longitudinal axis XX′ of the weapon and the traverse orientation axis. The first axis of rotation (G 1 ) is located to the rear of the weapon&#39;s ( 1 ) centre of gravity and the lateral range around the second axis (G 2 ) is of around 2°.  
     Application to armoured tracked vehicle

[0001] The technical scope of the present invention is that of layingsystems for a weapon ensuring its stabilisation.

[0002] When a weapon is mounted on a mobile support, that is on a movingvehicle, laying operations become difficult to ensure, since the weaponis subjected to a certain number of disturbances. Firing from such aweapon requires it to be oriented in the direction of the target andthis despite any movements, be they linear or angular, of the vehicle.One particularity of a vehicle able to move at high speeds (more than 50km/h) cross country lies in the stresses it causes to the weapon and toits laying system and which generally correspond to a high level andcover a wide spectrum.

[0003] During displacements of the vehicle, these disturbances maynotably come from:

[0004] the angular velocity of the support of which the weapon ismounted and which reach the weapon via the motorization system,

[0005] the linear acceleration applied to the turret's axis of rotationvia the offsetting the turret's centre of gravity with respect to thisaxis,

[0006] the angular acceleration applied directly to the turret by thefriction that appears on the circular bearing, friction caused inparticular by the sealing means to be set in place between the turretand the chassis,

[0007] the angular acceleration of the support around an axisperpendicular to the two traverse axes of rotation of the turret and theweapon's elevation axis of rotation via a coefficient depending on theelevation of the weapon.

[0008] Three types of limitations deteriorating the traverse orientationefficiency of the weapon may thus be found. Firstly, the weapon'spositioning accuracy is adversely affected by the friction because ofthe presence of a large diameter bearing and its associated seals.Moreover, on the one hand the motorization torque available for theturret limits the possibilities of compensating the roll effect on theorientation of the weapon, whereas on the other, the stabilisation errorassociated with this type of disturbance is particularly great.

[0009] Several methods and devices are known to attenuate the rolleffects on the firing performances of a weapon.

[0010] A first method consists in measuring the perturbing angularvelocity, for example using geometric type means, and using thismeasurement to control the rotational speed of the motorization systemplaced between the support and the weapon. It is thus an anticipatorycontrol placed in parallel with a servo control of the weapon's positionon an inertial reference whose efficiency is low so as to attenuate theamplitude of the angular disturbances at mean frequencies. Reference maybe made, for example, to patent FR-80.21077.

[0011] Another method consists in providing motorization means allowingthe torque applied to the load to be controlled. This principle is usedto improve the efficiency of the reduction of the effects of the angularvelocity disturbances. This method is adapted to low offset values.Reference may be made, for example, to patent U.S. Pat. No. 4,387,624.

[0012] Yet another method consists in measuring the gyrometric rollvelocity and in controlling an angular velocity of the turret that isproportional to this velocity, via a coefficient depending on theelevation of the weapon. Although this method allows the quality ofstabilisation provided by the servo-control of the weapon on theinertial reference to be improved, it is firstly limited in efficiencyand secondly rapidly reaches the limits of the motorization's torquecapacities.

[0013] When the elevation of the weapon and the angular roll velocitiesincrease, in spite of the quality of the controls given to the traversemotorization, the quality of the stabilisation deteriorates and thelimitations imposed by the size of the motorization in position arerapidly attained.

[0014] When driving cross country at high speed, two limitations thusdeteriorate the possibility of maintaining good traverse orientation ofa weapon laid on a target. Firstly, the weapon's positioning accuracy isaffected by the friction because of the presence of a large diameterbearing and its associated seals. Furthermore, on the one hand thetorque available for the motorization of the turret limits thepossibility of compensating the roll effect on the weapon's accelerationwhereas, on the other the error associated with this type of disturbanceis great.

[0015] The aim of the present invention is to propose a system thatexceeds the limits imposed by the traverse orientation of the weapon andsubstantially increases the range of compensation possible for the rolldisturbances.

[0016] The invention thus relates to a traverse laying system for aweapon integral with a frame articulated in traverse with respect to asupport providing a large traverse range around a first axis of rotation(G1), wherein it comprises positioning means for the weapon integralwith the frame or turret in order to ensure a small lateral range of theweapon around a second axis of rotation (G2) passing through the centreof gravity and perpendicular respectively to the longitudinal axis ofthe weapon and the traverse orientation axis.

[0017] According to one characteristic, the first axis of rotation (G1)is located to the rear of the weapon's centre of gravity.

[0018] According to another characteristic, the lateral range around thesecond axis is of around 2°.

[0019] According to another characteristic, the positioning meanscomprise a mantlet supporting the weapon and integral with the frame androtation control means.

[0020] According to another characteristic, the weapon is mounted bymeans of a joint with respect to the mantlet, with the positioning meansensuring the rotation of the weapon with respect to the mantlet aroundthe second axis (G2).

[0021] According to another characteristic, the joint is of themechanical or flexible type.

[0022] According to another characteristic, the mechanical joint isconstituted by a trunnion integral with a cradle placed between theweapon and the mantlet, and bearings integral with the mantlet.

[0023] According to another characteristic, the control means are a jackwhose body is integral with the mantlet and whose rod is connected tothe weapon.

[0024] According to another characteristic, the control means are a jackwhose body is integral with the weapon and whose rod is connected to themantlet.

[0025] According to another characteristic, the flexible joint isconstituted by two trunnions integral with the cradle and connected tothe mantlet by flexible means of low angular stiffness around axis G2and high stiffness around elevation axis S.

[0026] According to another characteristic, the secondary articulationmeans around axis G2 are obtained by the displacement in the oppositedirection of two eccentrics.

[0027] According to another characteristic, the control means areconstituted by two jacks working in opposite directions whose bodies arefastened to the cradle and whose rods are fastened respectively on eachof the eccentrics, the minimal flexibility of this motorization beingproduced by the radial stiffness of elastomer crowns.

[0028] A first advantage of the system according to the invention liesin the satisfaction of the absolute orientation quality requirements tobe imposed on the weapon through the adoption of a second joint at thecentre of gravity allowing a lateral angular displacement of the weaponwith respect to the turret.

[0029] Another advantage lies in the control of the traverse orientationof the weapon without disturbance to the elevation control.

[0030] Another advantage lies in the fact that the disturbing torquesapplied between the mantlet and the weapon via the second axis ofrotation G2 are limited to the driving torque and to the torque causedby the sealing system between the mantlet and the weapon's cradle.

[0031] Since the relative mantlet/cradle range is limited, specificsealing means (of the bellows type, for example) may be used to minimisethe parasitic constraints.

[0032] An additional advantage corresponds to the fact that maintainingthe weapon oriented on the target no longer requires the preciserotation of the turret with its associated constraints on the controlquality and on the maximum available torque.

[0033] Another advantage corresponds to being able to use the principledescribed in the US patent to motorise the additional axis of rotationG2 with its associated advantages on the positioning quality of theweapon. The corresponding motorization may either be electrical orhydraulic.

[0034] An additional advantage of the invention is that the turret'sstabilisation quality in traverse can be degraded, the residual errorsof the turret being taken up by the additional lateral orientationsystem.

[0035] Other characteristics, particulars and advantages of theinvention will become more apparent from the following description givenby way of illustration in relation to the appended drawings, in which:

[0036]FIG. 1 is a side section view of the weapon,

[0037]FIG. 2 is a top section view along the longitudinal axis of theweapon,

[0038]FIG. 3 is a section view of the weapon showing another example ofarticulation,

[0039]FIG. 4 is a section view of a flexible joint,

[0040]FIG. 5 is a section view of the weapon along longitudinal axis XX′showing another example of flexible articulation, and

[0041]FIG. 6 is a section view along EE in FIG. 5.

[0042] We know that a weapon mounted on an armoured vehicle classicallyincorporates a cradle mounted fixed with respect to a mantlet that isarticulated around a trunnion axis with respect to the turret or frame.The weapon thus incorporates a recoiling mass that slides longitudinallyin the cradle when the weapon is fired.

[0043] When the elevation angle of the weapon increases, the angularmovements of the vehicle around the roll axis have a direct effect onthe weapon's orientation. When this disturbance needs to be compensated,firstly, despite efficient control commands, the sensitivity of theresidual error with respect to the disturbance is relatively great and,secondly, the limitation imposed by the maximum acceleration torquedimensioning of the turret's motorization is rapidly attained.

[0044] According to the invention, a secondary lateral angular mobilityis provided between the cradle and the mantlet connecting it to theturret. This structure makes a rotation possible around an axisperpendicular to the axis of the weapon and to the axis of rotation inelevation, since the weapon is prevented from being driven in roll bythe turret and the means to access the available stabilisationefficiency are provided for a system that can take advantage of inertialstabilisation. Furthermore, since the main traverse motorization of theturret has a limited acceleration torque, when this saturation isreached stabilisation may be retained within the limits of the rangeprovided by the second joint allowing the secondary lateral angularmobility mentioned previously.

[0045] Preferentially, the secondary axis of articulation is placedaxially at the centre of gravity of the articulated laterally mass so asto limit the disturbance caused by the radial acceleration and to limitthe dimensioning of the secondary motorization.

[0046] As is apparent from the above, the invention consists inproviding an additional articulation of the weapon with respect to itsframe. A first, or main, joint allows the weapon to be classicallyoriented in traverse. This joint allows the weapon to be positionedwithout any angular limitation. A second joint allow the weapon to beoriented in traverse over a limited range and with no elevation and moregenerally laterally. The advantage of such a system according to theinvention lies in the fact that the secondary range between the weaponand the mantlet is, for example, limited to the stabilisation errorsaround the first axis making it easy to produce. Secondly, since thedimensioning of the second motorization is only linked to the inertia ofthe weapon to be oriented, efficient torque control may be made withoutany specific constraints.

[0047]FIG. 1 schematically shows a vertical section of a weapon 1mounted on a frame 2 itself mounted on a support 3 by means of a largediameter bearing 4. The support 3 is represented, for example, by theroof of an armoured vehicle, either tracked or wheeled. The frame 2, orturret, constitutes the interface between the weapon and the support andit supports the weapon by means of a trunnion 5 that can be seen in theFigure. Classically, the weapon is mounted in a mantlet 6 a with respectto which it slides inside a cradle 6 b during firing. The weapon is thusconnected to this mantlet by a certain number of mechanisms, notablybrakes, known in themselves and which do not require further descriptionto be able to understand the invention.

[0048] The weapon is mobile in elevation in a known manner with respectto the trunnion 5, for example by using a jack 7 connecting the mantletto the frame 2. It is also mobile in traverse with respect to thesupport 3 around a main axis G1.

[0049] According to the invention, the weapon 1 is mobile in rotationwith respect to the mantlet 6 a around an axis G2. In the embodimentdescribed, axis G2 is shown passing through the weapon's centre ofgravity and axis G1 is located to the rear of the centre of gravity.This arrangement has been preferentially selected, but it goes withoutsaying that axis G1 may occupy any intermediate position.

[0050]FIG. 2 shows a top view of the weapon 1 along a section made alongits longitudinal axis XX′. This Figure shows the path 8 of travel of theframe 2 or turret with respect to the support. This turret may be mobilein traverse rotation around axis G1 for an angle of 360°. The turretthus drives the weapon 1 to orient it in traverse with no elevation, orlaterally. To this end, a motor 9 drives the turret 2 by means ofreduction gear 10. The weapon 1 is thus mounted on the frame 2 by meansof a mantlet 6 a itself connected to the frame by two bearings 11 a and11 b. Bearings 11 a and 11 b define an elevation axis S of the weaponaround which it is driven in rotation by a back-geared motor.

[0051] According to one particularity of the invention, the secondtraverse axis G2 around which the weapon will be activated so as toorient it precisely. A joint is thus provided between the weapon 1 andthe mantlet 6 a and the rotation of said weapon is ensured by rotationcontrol means 14. These means may be, for example, a motor or jack. Thebody of the jack may be integral with the mantlet and its rod connectedto the weapon, or else the body of the jack is integral with the weaponand its rod with the mantlet.

[0052] Thanks to this arrangement, a rotation of around 2° of the weaponmay be obtained laterally thanks to the positioning means constituted bythe mantlet 6 a and the jack 14. Thus, the weapon may be preciselyoriented whatever the roll of the vehicle.

[0053]FIG. 3 shows a schematic view of the secondary lateralarticulation of the weapon 1 with respect to the frame 2 and to bearings11 a and 11 b linking it to the mantlet. The Figure illustrates thearticulation between the cradle 6 b and the mantlet 6 a. To this end,the cradle 6 b supporting the weapon 1 is connected to the mantlet 6 aby a joint 15 to ensure the secondary rotation of said weapon withrespect to the mantlet around the second axis G2. In this embodiment,the joint is of the mechanical type and comprises a trunnion 16 engagedin two bearings 17 and 18.

[0054] The joint may be of the flexible type. FIG. 4 shows an embodimentof a flexible joint. It is constituted by a metallic cylinder 19 intowhich the cradle is fastened and which is connected by plates ofelastomer 20 to the mantlet 6 a by means of a suitable matching part 21.Part 21 is made in two separate parts 21 a and 21 b for reasons ofcommodity during assembly and are rigidly fastened to the mantlet 6 a.In this type of joint, the flexible plates 20 are defined by theirmaterial firstly to give great stiffness and strength to withstand theaxial stresses due to the weapon recoil and, secondly, to have arelatively reduced stiffness with respect to the angular range intraverse up to around 2°. The stiffness associated with this degree offreedom corresponds approximately to a maximal load that must be limitedto between 10 and 20% of the maximal load of the associated secondarymotorization. A lateral radial stiffness is also specified, parallel tothe trunnion axis of the mantlet, that is enough to minimise its effecton the torquing dynamic of the secondary lateral motorization.

[0055] More generally, any articulation means may be provided betweenthe cradle and the mantlet allowing a small angular rotation around axisG2. These means must have a limited torque is the range limit aroundthis axis, must be able to transmit the recoil stresses from the weaponto the mantlet, and must have great angular stiffness around theelevation axis between the mantlet and the cradle.

[0056] When the weapon 1 has to be oriented, the following operationsare carried out. First of all the elevation and traverse angles of theweapon are set in a classical manner. Then, the weapon is finelypositioned by activating the jack 14. The weapon 1 will thus swivel,according to FIG. 3, at the trunnions 16 driving the cradle 6 b, themantlet 6 a being in a fixed position thanks to the elevation jack 7.This rotation is naturally carried out for a very small angle of around2°. According to FIG. 4, when the jack 14 is activated, the cylinder 19will swivel with respect to the connecting part 21 and the weapon isable to occupy maximal positions 1′ and 1″ shown on either side of axisXX′.

[0057] Other variant embodiments of the lateral orientation system ofthe weapon 1 can be envisaged. For example, an articulation may be madefor the weapon using two bearings embedded in one another and separatedby an eccentric. FIGS. 5 and 6, which are sections along longitudinalaxis XX′ of the weapon, show this embodiment. The weapon 1 is mounted ona turret 25 by a cradle/mantlet assembly 26 using two bearings 27 and 28separated by an eccentric 29. The external bearing 27 is large in sizeand surrounds the internal bearing 28. Bearing 28 allows the cradle 26to be connected using a trunnion 30, bearing 28 being itself supportedby bearing 27, fastened to the turret 25 by means of an elastomer crown31. This flexible crown works by shearing to allow the axis of bearings27 and 28 to remain in a perpendicular plane to the weapon axis. Theradial stiffness of these flexible links, relatively greater than thetangential stiffness, is used to impose an angular stiffness in therelative lateral chain of motorization between the weapon and theturret. FIG. 6 shows the eccentric in the form of a ring-shaped partwhose outer wall constitutes the inner race of bearing 27 and whoseinner wall constitutes the outer race of bearing 28.

[0058] To ensure the low lateral range of the weapon two jacks 32 and 33are provided, one of which pushes and the other pulls so as to drive theeccentrics 29 a and 29 b, thereby causing the weapon to rotate withrespect to the bearing 27 and thus with respect to the turret. Therotation of the eccentrics 29 a and 29 b in the opposite direction thusallows a lateral angular range of the weapon with respect to the turretand between two limits 1′ and 1″.

[0059] To position the weapon, an absolute position inertial sensorconstituted by a gyroscope is used which serves as a reference for theline of sight, the weapon and the mantlet. The gyroscopic sensor ispreferentially mounted on the mantlet and may be replaced by a gyrometerthat measures the angular velocity of the mantlet, such velocity beingintegrated so as to materialise the gyroscopic reference position. Theabsolute position of the cradle is computed using a linear positionmeasurement made in the vicinity of the actuator allowing a torque to beexerted on the weapon. According to the bending stiffnesses of themantlet and the crushing stiffness of the mantlet-cradle link it ispossible for an observer to estimate the radial strain between theweapon's axis of articulation and the tangent at the mantlet, on thetrunnions.

1. A traverse laying system for a weapon (1) integral with a frame (2)articulated in traverse with respect to a support (3) providing a largetraverse range around a first axis of rotation (G1), wherein itcomprises positioning means (6 a, 6 b, 14) for the weapon (1) integralwith the frame (2) in order to ensure a small lateral range of theweapon around a second axis of rotation (G2) passing through the centreof gravity and perpendicular respectively to the longitudinal axis XX′of the weapon and the traverse orientation axis.
 2. A laying systemaccording to claim 1, wherein the first axis of rotation (G1) is locatedto the rear of the weapon's (1) centre of gravity.
 3. A laying systemaccording to claims 1 or 2 claim 1, wherein the lateral range around thesecond axis (G2) is of around 2°.
 4. A laying system according to claim3, wherein the positioning means comprise a mantlet (6 a) and a cradle(6 b) supporting the weapon (1) and integral with the frame (2) androtation control means (14).
 5. A laying system according to claim 4,wherein the weapon (1) is mounted by means of a joint (15) with respectto the mantlet (6 a), with the positioning means (14) ensuring therotation of the weapon (1) with respect to the mantlet (6 a) around thesecond axis (G2).
 6. A laying system according to claim 5, wherein thejoint (15) is of the mechanical or flexible type.
 7. A laying systemaccording to claim 6, wherein the mechanical joint is constituted by atrunnion (16) integral with a cradle (6 b) placed between the weapon (1)and the mantlet (6 a), and bearings (17, 18) integral with the mantlet(6 a).
 8. A laying system according to any one of claims 5 to 7 claim 5,wherein the control means (14) are a jack whose body is integral withthe mantlet (6 a) and whose rod is connected to the weapon (1).
 9. Alaying system according to any one of claims 5 to 7 claim 5, wherein thecontrol means (14) are a jack whose body is integral with the weapon (1)and whose rod is connected to the mantlet (6 a).
 10. A laying systemaccording to claim 6, wherein the flexible joint is constituted by twotrunnions integral with the cradle (6 b) and connected to the mantlet (6a) by flexible means of low angular stiffness around axis G2 and highstiffness around elevation axis S.
 11. A laying system according toclaim 10, wherein the secondary articulation means around axis G2 areobtained by the displacement in the opposite direction of two eccentrics(29 a, 29 b).
 12. A laying system according to claims 10 or 11 claim 10,wherein the control means are constituted by two jacks (32, 33) workingin opposite directions whose bodies are fastened to the cradle (26) andwhose rods are fastened respectively on each of the eccentrics (29 a, 29b), the minimal flexibility of this motorization being produced by theradial stiffness of elastomer crowns (31).
 13. A laying system accordingto claim 2, wherein the lateral range around the second axis (G2) is ofaround 2°.
 14. A laying system according to claim 6, wherein the controlmeans (14) are a jack whose body is integral with the mantlet (6 a) andwhose rod is connected to the weapon (1).
 15. A laying system accordingto claim 7, wherein the control means (14) are a jack whose body isintegral with the mantlet (6 a) and whose rod is connected to the weapon(1).
 16. A laying system according to claim 6, wherein the control means(14) are a jack whose body is integral with the weapon (1) and whose rodis connected to the mantlet (6 a).
 17. A laying system according toclaim 7, wherein the control means (14) are a jack whose body isintegral with the weapon (1) and whose rod is connected to the mantlet(6 a).
 18. A laying system according to claim 11, wherein the controlmeans are constituted by two jacks (32, 33) working in oppositedirections whose bodies are fastened to the cradle (26) and whose rodsare fastened respectively on each of the eccentrics (29 a, 29 b), theminimal flexibility of this motorization being produced by the radialstiffness of elastomer crowns (31).